Initiation of human parturition: signaling from senescent fetal tissues via extracellular vesicle mediated paracrine mechanism

Ramkumar Menon 대한산부인과학회 2019 Obstetrics & Gynecology Science Vol.62 No.4

A better understanding of the underlying mechanisms by which signals from the fetus initiate human parturitionis required. Our recent findings support the core hypothesis that oxidative stress (OS) and cellular senescence ofthe fetal membranes (amnion and chorion) trigger human parturition. Fetal membrane cell senescence at term is anatural physiological response to OS that occurs as a result of increased metabolic demands by the maturing fetus. Fetal membrane senescence is affected by the activation of the p38 mitogen activated kinase-mediated pathway. Similarly, various risk factors of preterm labor and premature rupture of the membranes also cause OS-inducedsenescence. Data suggest that fetal cell senescence causes inflammatory senescence-associated secretory phenotype(SASP) release. Besides SASP, high mobility group box 1 and cell-free fetal telomere fragments translocate from thenucleus to the cytosol in senescent cells, where they represent damage-associated molecular pattern markers (DAMPs). In fetal membranes, both SASPs and DAMPs augment fetal cell senescence and an associated ‘sterile’ inflammatoryreaction. In senescent cells, DAMPs are encapsulated in extracellular vesicles, specifically exosomes, which are 30–150nm particles, and propagated to distant sites. Exosomes traffic from the fetus to the maternal side and cause laborassociatedinflammatory changes in maternal uterine tissues. Thus, fetal membrane senescence and the inflammationgenerated from this process functions as a paracrine signaling system during parturition. A better understandingof the premature activation of these signals can provide insights into the mechanisms by which fetal signals initiatepreterm parturition.

Influence of light qualities on antifungal lipopeptide synthesis in Bacillus amyloliquefaciens JBC36

Ramkumar, Gandhimani,Yu, Sang-Mi,Lee, Yong Hoon Springer-Verlag 2013 European Journal of Plant Pathology Vol.137 No.2

Quantum-Dot and Polychalcone Mixed Nanocomposites for Polymer Light-Emitting Diodes

Ramkumar, Vanaraj,Ju, Sanghyun Hindawi Limited 2017 Journal of nanomaterials Vol.2017 No.-

<P>The present work is aimed at improving the efficiency of light-emitting diodes (LEDs) through the amalgamation of polymeric materials and quantum dots (QDs) in nanocomposites. Herein, we report on the polytriphenylamine-based chalcone (PTpC) or polycarbazole-based chalcone- (PCzC-) QDs mixture nanocomposites as emissive layers for polymer LEDs (PLEDs). QDs were evenly dispersed in the polymer matrix and the synthesized PTpC-QDs and PCzC-QDs nanocomposites were able to form smooth thin films. The luminance characteristics of PTpC-QDs and PCzC-QDs nanocomposites were better than those of the pristine QD, PTpC, and PCzC materials, owing to the high charge-carrier transport ability of polymer-QDs nanocomposites. These results indicate that the proposed polymer-QDs nanocomposites could be potential candidates for application in PLEDs.</P>

Unraveling the link between severe bradycardia and paraquat poisoning

Ramkumar Anitha,Murthy Tatavarti,Elanjeran Rajkumar,Chaitanya Y. Vishnu,Harika Kari,Mahalingam Sasikumar,Rajendiran Gunaseelan 대한응급의학회 2024 Clinical and Experimental Emergency Medicine Vol.11 No.1

Epithelial to mesenchymal transition (EMT) of feto-maternal reproductive tissues generates inflammation: a detrimental factor for preterm birth

Ramkumar Menon 생화학분자생물학회 2022 BMB Reports Vol.55 No.8

Human pregnancy is a delicate and complex process wheremultiorgan interactions between two independent systems, themother, and her fetus, maintain pregnancy. Intercellular interactionsthat can define homeostasis at the various cellular levelbetween the two systems allow uninterrupted fetal growth anddevelopment until delivery. Interactions are needed for tissueremodeling during pregnancy at both fetal and maternal tissuelayers. One of the mechanisms that help tissue remodeling isvia cellular transitions where epithelial cells undergo a cyclictransition from epithelial to mesenchymal (EMT) and back frommesenchymal to epithelial (MET). Two major pregnancy-associatedtissue systems that use EMT, and MET are the fetal membrane(amniochorion) amnion epithelial layer and cervical epithelialcells and will be reviewed here. EMT is often associatedwith localized inflammation, and it is a well-balanced processto facilitate tissue remodeling. Cyclic transition processes areimportant because a terminal state or the static state of EMTcan cause accumulation of proinflammatory mesenchymal cellsin the matrix regions of these tissues and increase localizedinflammation that can cause tissue damage. Interactions thatdetermine homeostasis are often controlled by both endocrineand paracrine mediators. Pregnancy maintenance hormoneprogesterone and its receptors are critical for maintaining thebalance between EMT and MET. Increased intrauterine oxidativestress at term can force a static (terminal) EMT and increaseinflammation that are physiologic processes that destabilizehomeostasis that maintain pregnancy to promote labor and deliveryof the fetus. However, conditions that can produce anuntimely increase in EMT and inflammation can be pathologic. These tissue damages are often associated with adverse pregnancycomplications such as preterm prelabor rupture of themembranes (pPROM) and spontaneous preterm birth (PTB). Therefore, an understanding of the biomolecular processes thatmaintain cyclic EMT-MET is critical to reducing the risk ofpPROM and PTB. Extracellular vesicles (exosomes of 40-160nm) that can carry various cargo are involved in cellular transitionsas paracrine mediators. Exosomes can carry a variety ofbiomolecules as cargo. Studies specifically using exosomes fromcells undergone EMT can carry a pro-inflammatory cargo andin a paracrine fashion can modify the neighboring tissue environmentto cause enhancement of uterine inflammation.

Coupled temperature-displacement modeling to study the thermo-elastic instability in disc brakes

Ramkumar, E.,Mayuram, M.M. Techno-Press 2012 Coupled systems mechanics Vol.1 No.2

Macroscopic hot spots formed due to the large thermal gradients at the surface of the disc brake rotor, make the rotor to fail or wear out early. Thermo-elastic deformation results in contact concentration, leading to the non uniform distribution of temperature making the disc susceptible to hot spot formation. The formation of one hot spot event will predispose the system to future hot spotting at the same location. This leads to the complete thermo-elastic instability in the disc brakes; multitude parameters are responsible for the thermo elastic instability. The predominant factor is the sliding velocity and above a certain sliding velocity the instability of the brake system occurs and hot spots is formed in the surface of the disc brake. Commercial finite element package ABAQUS(R) is used to find the temperature distribution and the result is validated using Rowson's analytical model. A coupled analysis methodology is evolved for the automotive disc brake from the transient thermo-elastic contact analysis. Temperature variation is studied under different sliding speeds within the operation range.

Optimization of operating parameters and performance evaluation of forced draft cooling tower using response surface methodology (RSM) and artificial neural network (ANN)

Ramkumar Ramakrishnan,Ragupathy Arumugam 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"Optimization of cold water temperature in forced draft cooling tower with various operating parameters has been considered in the present work. In this study, response surface method (RSM) and an artificial neural network (ANN) were developed to predict cold water temperature in forced draft cooling tower. In the development of predictive models, water flow, air flow, water temperature and packing height were considered as model variables. For this propose, an experiment based on statistical five-level four factorial design of experiments method was carried out in the forced draft cooling tower. Based on statistical analysis, packing height, air flow and water flow were high significant effects on cold water temperature, with very low probability values (< 0.0001). The optimum operating parameters were predicted using RSM, ANN model and confirmed through experiments. The result demonstrated that minimum cold water temperature was optioned from the ANN model compared with RSM."

A Tinnitus Inventory Focusing on Body Function, Activities, and Participation Using the International Classification of Functioning, Disability and Health

Ramkumar Vidya,Chandrasekaran Anitha 대한청각학회 2023 Journal of Audiology & Otology Vol.27 No.2

Background and Objectives: This study describes the development of an International Classification for Functioning, Disability and Health (ICF)-based inventory for tinnitus (ICF-TINI) that measures the impact of tinnitus on the function, activities, and participation of an individual.Subjects and Methods: This cross-sectional study utilized the ICF-TINI, which included 15 items from the two ICF components of body function and activities. We included 137 respondents with chronic tinnitus. Confirmatory factor analysis validated the two-structure framework (body function, activities and participation). The model fit was assessed by comparing fit values of chi-square (df), root mean square error of approximation, comparative fit index, incremental fit index, and Tucker-Lewis index, with the suggested fit criteria values. Cronbach’s alpha was used to assess internal consistency reliability.Results: The fit indices confirmed the presence of two structures in ICF-TINI, while the factor loading values suggested each item’s goodness of fit. The ICF-internal TINI exhibited high consistency reliability (0.93).Conclusions: The ICFTINI is a reliable and valid tool for assessing the impact of tinnitus on an individual’s body function, activities, and participation.

Experimental Evaluation of Evaporative Cooler Using Agro Materials

R. RAMKUMAR,M. Kesavan,A. RAGUPATHY 대한설비공학회 2015 International Journal of Air-Conditioning and Refr Vol.23 No.4

The purpose of the study is to investigate the direct evaporate cooler in hot and humid regions with two different types of agro-based materials. In our experimental study, the locally available agro materials luffa (Sponge Gourd), zizanioides (Vetiver) were used with various thickness and the experimental results were compared with mathematical values. The operating parameters of pad thickness, air velocity, were changed and the performance of the cooler was analyzed. A test rig was designed and fabricated to collect experimental data. The performance of the evaporative cooler was evaluated based on the ambient condition. The analysis of the data indicated that cooling saturation efficiency improve with decrease of air velocity and higher pad thickness. It was shown that zizanioides-based pad with 160mm thickness has the higher performance (88%) at 4.5 m/s air velocity in comparison with luffa pad materials. The experimental results of outlet air temperature and number of transfer units (NTU) were compared with mathematical model. The test results were within the limit of 15% and 10% to mathematical values.

Flow Stress Modeling for Copper under Changing Process Conditions

Oruganti, Ramkumar K .,Rao, K . P . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3

Realistic simulation of metal forming processes requires constitutive equations that describe the behavior of a material under varying process conditions. The equations that have hitherto been developed to address this problem are generally too involved and require the determination of many constants. In this paper, a simple approach based on the representative nature of the work hardening rate, which enables the use of an elementary rate equation in such modelling, is introduced. A prediction methodology based on the concept of fading memory is developed and is found to give good predictions in the case of copper. A mechanistic interpretation of the approach is proposed.